Prior art devices designed to cope with backlash approach the problem by means of springs disposed to put a torsional bias on a gear. Such devices are unsatisfactory in that they are too expensive, unreliable from the accuracy point of view, and too expensive to maintain. Fire control systems require a high degree of accuracy in order to come at all close to a first-round hit capability, because the accuracy of enemy fire and the speed and fluidity of movement in modern war are such that one chance at the target may be all the gunner will get.